Apparatus for stretching travelling filaments consisting of fully synthetic plastics



March 9, 1965 w. RODENACKER ETAL 3,172,136

APPARATUS FOR STRETCHING TRAVELLING FILAMENTS SISTING 0F FULLY SYNTHETIC PLASTICS CON Filed July 21. 1960 4 Sheets-Sheet. 1

WOLFRGJEMGGR, HE/NZ WEGNER. INVENTOR an W A TTORNEYS FIGS March 1965 r w. RODENACKER ETAL 3,172,186

APPARATUS FOR STRETCHING TRAVELLING FILAMENTS CQNSISTING OF FULLY SYNTHETIC PLASTICS Filed July 21. 1960 4 Sheets-Sheet 2 INVENTORS.

WOLF RODENACKEP, HE/NZ WEGQII ER. y]

6W1, A TTOPNEYS March 1965 w. RODENACKER ETAL 3, 7 86 APPARATUS FOR STRETCHING TRAVELLING FILAMENTS CONSISTING OF FULLY SYNTHETIC PLASTICS Flled July 21 1960 4 Sheets-Sheet 3 INVENTORS.

WOLF RODENACKER, HE/NZ WEGQ/YEP pf g j Mr 7? A T TO RNE Y5 March 9, 1965 w. RODENACKER ETAL 3,172,186

APPARATUS FOR STRETCHING TRAVELLING FILAMENTS CONSISTING 0F FULLY SYNTHETIC PLASTICS Filed July 21. 1960 4 Sheets-Sheet 4 42 4] FIG. 8

INVENTORS. WOLF RODE NACK E P, HE lNZ WE GNE P.

A TTORNEKS United States Patent APPARATUS FOR STRETCEHNG TRAVELLENG FILAM ENES ,CQNSISTING 0F FULLY SYN- TIETIC PLASTICS Wolf Rodenacker and Heinz Wagner, Dormagen, Germany, assignors to Farheniahrilren Bayer Alr'tiengesellschait, Leverlrusen, Germany, a corporation oi Germany Filed July 21, 1960, Ser. No. Claims priority, application Germany,

July 23, 1959, 295903 2 Claims. (Cl. 28- -71.3) This invention relates to an apparatus for stretching traveling filaments consisting of fully synthetic plastics.

A fully synthetic filament is usually stretched between two roller systems which are driven at different speeds, the roller systems running at constant speeds of revolution which are adjusted to the required stretching ratio. In this way, each portion of the filament is lengthened by a constant amount. Fluctuations in the count of the initial material cause fluctuations of the drafting force in the drafting zone with this stretching method. These fluctuations in the count permit a stretching of the material only up to the lower limiting value of the fluctuating drafting forces as otherwise overstrctching would be liable to occur. The filament is certainly lengthened to a constant degree, but atthe sametime would be unevenly stressed if overstretching were permitted. The filament leaving the drafting zone still shown fluctuations in the count.

In order to reduce these count fluctuations of the stretched filament, it has already been proposed to draw the filament through a drawing nozzle. A filament which is stretched in this way and which, before reaching the nozzle, has the same count fluctuations as before reaching the drawing zone certainly shows a smaller count fluctuation when stretching with constant elongation than when the drafting method with constant elongation is used but has however an undesirable distribution of weak areas throughout the drafting length because too thick areas of the filament are overstressed at the nozzle. Consequently, the strength values which are produced are considerably lower than those obtained with a drafting process using constant lengthening.

It has now been found that the strength values can be considerably improved, while simultaneously reducing the fluctuations in diameter, if in accordance with the present invention the filament is drawn against an adjustable force kept constant at a grooved disc or roller, which force maintains the equilibrium of the drafting force exerted on the filament. In this way, the filament is loaded with a constant drafting force and consequently the filament can be stretched to an opitmum degree.

An apparatus for carrying the process into effect consists of a rotatably mounted grooved disc as the member for drawing or withdrawing the filament to be stretched, which disc is coupled to a brake device, the adjustable braking moment of which maintains the equilibrium of the torque exerted by the filament on the grooved disc. The brake is so adjusted that the filament can be stretched up to the maximum value of the constant drafting force, at which it no longer breaks, having regard to the initial count fluctuations. Constant fluctuations in length occur in the filament with the driving of the grooved disc, i.e. the grooved disc generally rotates at a peripheral speed which fluctuates as a function of time. The extent of this fluctuation depends on the initial count fluctuation and the flowing capacity of the actual material. If the material has a good flowing capacity, the grooved disc holds back the length of filament and therefore runs more slowly, while with a poor flow capacity, the grooved disc yields to the length of filament and therefore runs more the grooved disc is shown by idlzddfi Patented Mar. 9, 1965 quickly, in both cases with a constant drafting force. A self-regulating braking means for constant filament tension is preferably provided in the form of a gearwheel pump with a circulation system, the h using of the pump being mounted to pivot about its axis and being provided with an eccentrically acting adjustable weight and turns a torsion capillary arranged in the liquid circulation, the capillary being fixed at one end on the movable housing and at the other end at a fixed point. Y By greater or lesser constriction of the tube cross-sections, the torque of the gearwheel pump is so adjusted that the drafting force on the filament maintains the balance with the weight.

instead of the torsion capillary, it is also possible to provide a valve, the adjustable valve member of which is displaced relatively to a seating arranged in the pivotable housing when the housing turns. The braking means can be constructed as an electric eddy current brake.

Embodiments of the invention are shown diagrammatically in the drawing. PlGURE 1 schematically shows the arrangement in principle of an apparatus for stretching the filament with a constant drafting force. FIGURE 2 schematically shows the drafting means in conjunction with a calender drum. FIGURE 3 schematically shows the drafting means as a preliminary device in combination with the conventional inlet and outlet roller systems which are driven at difierent' speeds. FIGURES 4, 5 and 6 illustrate embodiments of drafting means com prising a grooved disc which is coupled with a brake means formed as a gearwheel pump, PlGURE' l being in perspective and FIGURES 5 and 6 being sections. FIG- URE 7 is a perspective view of an eddy current brake coupled with a grooveddisc. FIGURE 8 schematically shows the grooved disc coupled with a brake means and serving as a filament-withdrawal device for the spinning process.

According to FZGURE l, a filament 1 to be stretched runs from a bobbin 2 over a roller 3 to a grooved disc '4 which is coupled to a brake means 4a and is drawn off the grooved disc 4 against the braking force of the device do, by means of a roller system 5 and thus is stretched in the best possible manner. The finally stretched filament is wound on to a bobbin 7, after passing through a filament-laying device 6.

According to FIGURE 2, a filament 1 runs from a bobbin 2 over a roller 3 and over a braked grooved disc 42- with full tension on to a calender drum 8. By being repeatedly wrapped around the drum 8 by means of a laying roller 9; the filament is stretched to an optimum degree, is brought into contact with the hot rollerror drum Ss surface and is aftertreated in order subsequently to be wound on a bobbin 7 by way of a laying device 6.

FIGURE 3 represents the use of the drafting process as a preliminary stretching means for use with a final stretching roller mechanism with constant elongation. As before, a filament 1 is laid around a braked grooved disc 4 and is initially stretched in the zone between a disc A- and a roller mechanism ill. Between two roller systems 1i? and 11, the filament l experiences a final stretching up to about in order then to be again wound on to a bobbin 7.

The construction of a brake arrangement coupled to way of example in FIGURE 4. A grooved disc 4, in which a filament 1 is laid after passing over a roller 3, is mounted on a shaft 12 on which are also mounted gearwheels of a gearwheel pump13. This gearwheel pump conveys oil from a pipe 14 through a hollow shaft 15 and a torsion capillary 16, which is turned relatively to a fixed point 17 by means of an eccentrically acting weight 21 (thereby reducing its crosssection), and through a pipe 18 into an oil storage container l9. Owing to the mounting of the entire system in bearings Zfi, the torque which is exerted on the fila- Inent turns the entire system against the action of the weight 21 until the resistance of the torsion capillary and thus the torque at the gearwheel pump has become so large that the tension in the filament 1 and the counterweight 21 are in equilibrium.

The torsion capillary 16 is shown in greater detail in FIGURE 5. The torsion capillary is clamped at one end in a housing 22 and at the other end in the fixed point 17 and is so twisted when the housing 22 swivels that the cross-section available for the flow of oil is constricted and thus the oil pressure of the pump is increased.

FIGURE 6 shows another example of the automatic regulation of the torques. A gearwheel pump 13 within housing 22 regulates the oil through supply line 14 and conveys the oil towards a valve member 23 which is moved relatively to a valve seat 24 by rotation of the housing 22. 'A valve spindle 25 is retained in a square portion 26 of the fixed point 17. By means of a thread 27, the spindle can be so adjusted that the resistance in the oil circulation is increased or lowered according to the movement of the housing 22. The oil flows through a flexible tube 28 and a pipe 18 back to a container 19. The torque exerted on the filament through the disc 4 is brought into equilibrium with the weight 21 arranged on the pump housing 22, since the housing 22 is readily rotatable in ball bearings 29.

For stretching individual filaments, for example of monofil or multifil rayon, it is advantageous to use an arrangement such as shown in FIGURE 7, which corresponds in principle to the construction with an oil circulation (FIGURES 4- and 6). In this case, a filament 1 is guided over a driving disc 4 which carries, on the other side of a bearing 30 a disc 31 made of aluminium or copper. Arranged to be rotatable and axially displaceable opposite this disc in a threaded pedestal 33 is a soft-iron disc 32. The soft-iron disc 32 carries for example four magnets 34, each pair of which are opposite one another as North and South poles. When the disc 31 is moved, electric currents are induced in the disc 32. Owing to the turning movement of the grooved disc 4 and thus of the disc 31, the magnets 34 exert a braking moment on the disc 31 and also a counteracting moment on the disc 32 carrying the magnets. This moment is balanced by a weight 37 suspended from a disc 35 by means of a belt 36 so that, as the disc 32 is turned, it is simultaneously displaced to increase the air gap of the magnets and thus the torque is again reduced. The balancing of the torque of the filament drawing at the disc 4 and of the counter-weight 37 at the disc 35 is therefore effected through an eddy current brake automatically adjusting the air gap. The same principle can of course also be used in arrangements of more advanced design, but these do not enable the method of operation to be so clearly seen. The eddy current disc 31 can also be caused to project into a magnetic field. The holder of the associated magnets can be movably arranged, for example be balanced according to the principle of an inclination balance. The magnets and the disc 31 can also be coaxially arranged.

The principle illustrated can also be used at the discharge end of a drafting frame. This construction is suitable in all machines in which the inlet roller system of the drafting frame is simultaneously used with the withdrawal roller system for the spinning operation, which must run at a constant Withdrawal speed, in opposition to the brake. In this case, a constant drawing must be applied to the filament with the second withdrawal roller system. This can be explained by reference to FIGURE 8 in the following manner.

A withdrawal roller 38 which corresponds to the disc 4, is mounted on a shaft 39 which is connected to a sun wheel 40 of a differential. The differential is driven by a motor 41 through gearwheels 42 and 43. Fixed on the gearwheel 43 is a bevel gear 4-4 which meshes with the sun wheel 40 of the differential. A second bevel gear 45 of the differential is connected fast to a brake device 46, which corresponds substantially to that according to FIGURE 6. If the brake device 46 is locked, a rigid driving of the roller 33 is obtained. However, if the brake is released, the brake starts to rotate until the torque at the bevel gear 45 is equal to the torque on the shaft 39 produced by the drawing of the filament at the roller 38. Therefore, a predetermined constant filament drawing at the roller 38 corresponds to the braking moment, the said roller having the tendency to run more quickly until the force adjusted at the brake 46 is reached. In this way, it is possible to exert a constant drawing of the filament, also with a constant input speed of the filament into the drafting Zone.

A variation of the process consists in that the material arriving with a constant withdrawal from the spinning machine is collected in a storage means and the process is otherwise to be carried out in accordance with FIGURE 1. It is necessary however to regulate the speed of the roller system 5 (FIGURE 1) according to the filling of the magazine.

Example By means of an arrangement according to FIGURE 1, it is for example possible to produce the following measurement values on a 0.4 mm. filament:

The power stretching process according to the invention, as shown by the experimental example, has great advantages over the hitherto usual stretching methods. These advantages consist in the important increase in the E-modulus, in the likewise interesting improvement of the strength value and particularly in the reduction of the fluctuations in diameter of the material being processed. The machines for carrying out the process are of substantially more simple design and are also correspondingly less expensive, since only one additional roller or roller system is required. Owing to the saving of infinitely variable gears for adjusting the preferred stretching speed, which latter is automatically selected at the brake, savings in machine costs up to /s of the machines formerly in use are obtained. Owing to the simple design of the components, the brakes can be made to be reliable in operation and can be manufactured in large numbers. If the brake forces which occur are too strong, it is possible for a part of the braking energy to be recovered in a manner similar to FIGURE 8 through a differential which transmits part of the torque back to the driving gear. The brake can quite generally be used as a self-regulating filament brake.

We claim:

1. A filament stretching apparatus for stretching ad vancing artificial filaments comprising a rotatably mounted shaft, 9. filament drawing disc provided with a groove to engage said advancing filament and mounted on said shaft so as to be rotatable therewith, advancing means for said filament, fluid brake means characterized by an adjustable braking moment associated with said disc for imparting a retarding force to said disc balancing the torque exerted by the advancing filament on the grooved disc, said braking means comprising a gear pump containing gears situated within a gear pump housing, one of said gears being secured to said shaft and the other of said gears being rotatably mounted to said gear pump housing and said housing being mounted to swivel on said housings axis, said pump being adapted to pump fluid through a fluid circulation system via a torsion capillary, said capillary secured at one end thereof to the outlet on the pump housing and at the other end to a fixed point in the 'fluid circulation system, said torsion capillary being capable of rotation relative to said fixed point, the degree of said rotation being controlled by an eccentrically acting adjustable weight mounted on said pump housing whereby when said housing is caused to swivel the crosssectional area for the flow of fluid is constricted and the flow pressure in the pump increased whereby the tension in the filament and said weight is brought into equilibrium.

2. A filament stretching apparatus for stretching advancing artificial filaments comprising a rotatably mounted shaft, a filament drawing disc provided with a groove to engage said advancing filament and mounted on said shaft so as to be rotatable therewith, advancing means for said filament, a fluid braking means characterized by an adjustable braking moment associated with said disc for imparting a retarding force to said disc balancing the torque exerted by the advancing filament on the grooved disc, said braking means comprising a gear pump contain ing gears situated within a gear pump housing, one of said gears being secured to said shaft and the other of said gears being rotatably mounted to said gear pump housing and said housing being mounted for swiveling movement on said housings axis, said pump being adapted to pump fluid through a fluid circulation system via a valve member movable relative to a valve seat by the swiveling movement of said housing, the degree of said movement being controlled by an eccentrically acting adjustable weight mounted on said pump housing whereby when said housing is caused to swivel, the resistance in the area for the flow of fluid is increased and the flow pressure in the pump increased whereby the tension in the filament and said weight are brought into equilibrium.

References Cited in the file of this patent UNITED STATES PATENTS 2,586,037 Heflelfinger Feb. 19, 1952 2,605,061 Howe July 29, 1952 2,624,527 Von Kohorn Jan. 6, 1953 2,659,549 Galin Nov. 17, 1953 2,845,235 Wilcox July 29, 1958 2,932,078 Wilson Apr. 12, 1960 2,942,325 Spellman June 28, 1960 3,022,025 Saxl Feb. 20, 1962 

1. A FILAMENT STRETCHING APPARATUS FOR STRETCHING ADVANCING ARTIFICIAL FILAMENTS COMPRISING A ROTATABLY MOUNTED SHAFT, A FILAMENT DRAWING DISC PROVIDED WITH A GROOVE TO ENGAGE SAID ADVANCING FILAMENT AND MOUNTED ON SAID SHAFT SO AS TO BE ROTATABLE THEREWITH, AADVANCING MEANS FOR SAID FILAMENT, FLUID BRAKE MEANS CHARACTERIZED BY AN ADJUSTABLE BRAKING MOMENT ASSOCIATED WITH SAID DISC FOR IMPARTING A RETARDING FORCE TO SAID DISC BALANCING THE TORQUE EXERTED BY THE ADVANCING FILAMENT ON THE GROOVED DISC, SAID BRAKING MEANS COMPRISING A GEAR PUMP CONTAINING GEARS SITUATED WITHIN A GEAR PUMP HOUSING, ONE OF SAID GEARS BEING SECURED TO SAID SHAFT AND THE OTHER OF SAID GEARS BEING ROTATABLY MOUNTED TO SAID GEAR PUMP HOUSING AND SAID HOUSING BEING MOUNTED TO SWIVEL ON SAID HOUSING''S AXIS, SAID PUMP BEING ADAPTED TO PUMP FLUID THROUGH A FLUID CIRCULATION SYSTEM VIA A TORSION CAPILLARY, SAID CAPILLARY SECURED AT ONE END THEREOF TO THE OUTLET ON THE PUMP HOUSING AND AT THE OTHER END TO A FIXED POINT IN THE FLUID CIRCULATION SYSTEM, SAID TORSION CAPILLARY BEING CAPABLE OF ROTATION RELATIVE TO SAID FIXED POINT, THE DEGREE OF SAID ROTATION BEING CONTROLLED BY AN ECCENTRICALLY ACTING ADJUSTABLE WEIGHT MOUNTED ON SAID PUMP HOUSING WHEREBY WHEN SAID HOUSING IS CAUSED TO SWIVEL THE CROSSSECTIONAL AREA FOR THE FLOW OF FLUID IS CONSTRICTED AND THE FLOW PRESSURE IN THE PUMP INCREASED WHEREBY THE TENSION IN THE FILAMENT AND SAID WEIGHT IS BROUGHT INTO EQUILIBRIUM. 